An original copy of the Declaration of Independence, printed by Philadelphian John Dunlap on the day it was signed, was an honored guest yesterday at New Jersey's 345th birthday party.

The rare document and the original royal grant establishing the English colony of New Jersey on June 24, 1664, helped commemorate New Jersey Day. Both will remain on exhibit at the State Museum in Trenton today.

"We are so proud that we have a chance to display those two documents side by side," Gov. Jon S. Corzine said.

The Declaration of Independence is one of 25 known existing copies of the "Dunlap imprint." Dunlap printed 200 in his Philadelphia shop after Thomas Jefferson rushed the document to him July 4, 1776, according to New Jersey officials.

The only copy that travels around the country, it will be exhibited in six cities recognized for participation in last fall's National Student/Parent Mock Election campaign. The timing coincides with New Jersey's birthday.

Proud New Jerseyans came out in droves for the occasion, packing into the first floor of the museum and snapping pictures of the artifacts.

If anything outshined the documents, though, it was New Jersey's students.

The Pearson Foundation and Declare Yourself, a nonprofit youth voter-registration organization, chose the state for the tour because more than a quarter-million New Jersey students - out of more than five million nationwide - took part in the mock election. Several of the 802 New Jersey schools reported 100 percent participation.

When planning the anniversary celebration, Secretary of State Nina Mitchell Wells said, "we had no idea that we would receive the honor and distinction that we have received because of our fantastic, fantastic students."

In addition to congratulating the students, teachers, and principals involved in the mock election, ceremony officials honored several other groups of students for their accomplishments.

One student was Kristine Thomas, an eighth grader at Rosa International Middle School in Cherry Hill. Thomas and a team of fellow students represented New Jersey at a National History Day contest at the University of Maryland this month.

She enjoyed a piece of cake in celebration of New Jersey's birthday.

"It's a tiny state, but it means a lot to everyone," she said.

The ceremony concluded with a rousing version of "Happy Birthday," and the distribution of birthday cake and cupcakes sprinkled red, white, and blue.

Contact staff writer Megan DeMarco at 856-779-3844 or mdemarco@phillynews.com.